Mobile radio antennas for mobile radio base stations are normally constructed such that two or more antenna element arrangements, which are located one above the other, are provided in the vertical direction in front of a reflector plane. These antenna element arrangements are formed, for example, from dipoles or patch antenna elements. These may be antenna element arrangements which can transmit and/or transmit and receive at the same time. They can operate only in one polarization or, for example, in two mutually perpendicular polarizations. The entire antenna arrangement may be designed for transmission in one band or in two or more frequency bands by using, for example, two or more antenna elements and antenna element groups which are suitable for the various frequency bands.
Depending on the requirements, mobile radio antennas are generally used which have different length variants. The length variants often depend, inter alia, on the number of individual antenna elements or antenna element groups to be provided. Identical or similar antenna element arrangements are generally arranged repeatedly one above the other in such arrangements.
An antenna or an antenna array such as this may have a common reflector for all the antenna element arrangements. This common reflector is normally formed by a reflector plate which may be stamped, curved and/or bent depending on the requirements. For example, such reflector configuration makes it possible to form a reflector edge area, which projects forwards from the reflector plane, on the two opposite side vertical edges. Furthermore, if required, additional sheet-metal parts may be soldered on the reflector. The use of profiles is also known, for example extruded profiles made of aluminum etc., which are likewise fitted on or in front of the reflector plane.
Costly, complex, three-dimensional functional surfaces for the antenna element arrangements are advantageous, or even necessary, for certain applications. Until now, a large number of connecting points and contact points have generally been required on the reflector in order to produce such surrounding conditions for the antenna element arrangement. Some of the parts and components which are used are also still in some cases made of different materials. However, this can result in a number of disadvantages. For example, the large number of different parts and the major assembly effort associated with them can be disadvantageous. Overall, these can result in comparatively high production costs. Another possible disadvantage is the large number of contact points. A large number of contact points can contribute to undesirable intermodulation products. Adequate functional reliability can often be achieved by taking the greatest possible care during assembly. On the other hand, the antennas that are produced in this way generally have a restricted function and load capability since, particularly in the case of unsuitable material combinations or even if there are only a small number of bad contact points, it may not be possible to comply with the requirements relating to undesirable intermodulation products. If a test run of the checked polar diagram of an antenna reveals problems, then it is also not necessarily immediately possible to state which contact points may have contributed to the deterioration in the intermodulation characteristics.
The illustrative non-limiting exemplary technology described herein provides an improved capability to produce antennas with high quality characteristics, by means of which it is furthermore intended to be possible to produce antennas of different physical sizes with comparatively little complexity and to a high quality standard.
The illustrative non-limiting exemplary technology described herein proposes a solution for constructing different length variants of antennas with the same or a similar function with comparatively little complexity. The reflector devices may also be used for antennas of different construction which may, for example, hold different antenna elements or antenna element assemblies. Finally, even complex, three-dimensional surrounds with functional surfaces in the transverse and/or longitudinal direction or in other directions of the reflector can be produced using simple means. Functional surfaces such as these may also be produced, for example, aligned at an angle to the major axis, that is to say generally at an angle to the vertical axis in which the reflector extends.
At the same time, the exemplary illustrative non-limiting antenna or reflector configuration described herein makes it possible to considerably reduce the number of contact points. In turn, this makes it possible to reduce the large number of different parts and the assembly effort, with a high degree of functional integration as well.
The exemplary illustrative non-limiting implementations described herein provide for a reflector to be constructed from at least two separate reflector modules, which may be mounted jointly, for example in the vertical direction in an extension of their vertical axis. It is generally desirable to produce an overall arrangement which is mechanically robust from at least two or more reflector modules which can be fitted to one another in the vertical direction. It is also generally desirable to provide an overall arrangement furthermore with desired characteristic values from the electrical point of view for the antenna element arrangement which is provided on each reflector module.
Accordingly, in the exemplary illustrative non-limiting implementation, at least the basic version of each reflector module is formed integrally, specifically preferably using a casting, deep-drawing, thermoforming, stamping or milling method. The expression master gauge method can also be used in this connection in some cases. The reflector module may thus, for example, be formed from an aluminium cast part or generally from a metal casting or else from a plastic injection-molded part, which is then provided with a metalized surface on one surface, or at least on both opposite surfaces.
The exemplary illustrative non-limiting reflector module can also be produced using a tixo casting method or else, for example, by milling. In this case, the example reflector module implementation preferably has a circumferential rim, at least on its two longitudinal faces and on at least one narrower transverse face, but preferably on both of its longitudinal faces and on both of its end faces. Thus, lateral boundary webs or boundary surfaces may project transversely with respect to the reflector plane provided on the two opposite vertical faces. In addition, one or in each case one boundary web or a boundary surface may be provided on at least one of the end faces, and preferably on both opposite end faces.
Each reflector module may also have at least one fixed integrated central transverse web. Such a transverse web may comprise at least one upper and one lower field for antenna element arrangements which can be used there.
At least two antenna element surrounds may thus be defined for each reflector module. These antenna element surrounds may be produced by an end-face boundary wall, two sections of the vertical side longitudinal boundaries and the at least one web wall which runs transversely with respect to the side boundary walls.
A reflector module formed in this way may then also be suitable for being joined to at least one further reflector module, for example of the same physical type, at the end face to form an entire reflector arrangement with a greater vertical extent.
One exemplary illustrative non-limiting implementation provides for a final reflector to be formed from at least two reflector modules which are joined together with the same orientation. In an alternative exemplary illustrative non-limiting refinement, it is also possible to join the end faces of two reflector modules together, with the two reflector modules being aligned with their basic shapes at 180° to one another. This exemplary non-limiting assembly has been found to be particularly advantageous when the two opposite end face surfaces have different shapes, that is to say when only one end face surface is suitable for actually joining it to a next reflector module.
Reflector modules may also be joined together with different shapes but with a comparable basic structure, as described above.
As is known, the forces which act on a reflector and the operating loads which are produced by the actions of these forces, for example resulting from vibration, wind and storms, should not be underestimated. Loads such as these naturally occur particularly strongly at the junction point in an exemplary illustrative non-limiting reflector arrangement when using at least two modules whose end faces are joined together. However, moving and undefined contacts should generally also not be used in order to avoid undesirable intermodulation problems.
One exemplary illustrative non-limiting implementation therefore provides for the corresponding end walls to be appropriately matched for joining together at least two reflector modules. For this purpose, they preferably may have attachment points which are offset with respect to one another in two planes. This makes it possible firstly to transmit and to absorb comparatively large moments, while at the same time providing functionally reliable electrical contact points. An electrically conductive contact can be made between the two reflector modules in the area of their end walls that are joined together. Or, they can also be connected to one another without any electrically conductive connection, for example by inserting an insulating intermediate layer, for example a plastic layer or some other dielectric, between them. In some circumstances, a damper material can also preferably be used for the intermediate joint for an insulating layer such as this, which means that the two reflector module halves may even oscillate to a certain extent with respect to one another, to a restricted extent, in a severe storm. This thus serves to improve mechanical reliability.
The offset plane of the attachment points, that has been mentioned, also serves to ensure that shape discrepancies are not additive at the connecting interface. If necessary, such phenomenon can be compensated for with comparatively few problems, in such a way that production tolerances can be compensated for. If, for optimization of the polar diagram of an antenna, it is necessary or desirable to attach additional metallic elements at specific points in the reflector, then, in one exemplary illustrative development, these additional elements may be used, for example, in the form of electrically conductive strips, webs etc., by means of separate holding devices. For example, electrically nonconductive holding devices can be preferably formed from plastic or from some other dielectric. They can be fitted to the existing intermediate webs or side boundary wall sections. In one exemplary illustrative implementation, between the holding devices, the metallic elements which have to be inserted in addition can then be hooked in. This capacitive anchoring then once again furthermore avoids undesirable intermodulation products.
One exemplary illustrative non-limiting implementation provides for a reflector module which has been produced using a casting, deep-drawing, thermoforming or stamping method. Alternatively, a milling method can be used. Further integrated parts, or parts of further components, which are required in particular in conjunction with an antenna can be provided, on the rear face of the reflector module, opposite the antenna element modules for example. This allows functional integration to be achieved in the reflector, associated with further significant advantages.
In exemplary illustrative implementations, the following functional elements may, for example, be integrated in the reflector module without any problems:
It is thus possible also to integrally form outer conductor contours for carrying radio-frequency signals, for example a grooved cable, coaxial cable, stripline etc., on the front face or else in particular also on the rear face of the reflector.
In the same way, contours may be integrally formed for electromagnetic screening of assemblies.
Housing parts for RF components such as filters, diplexers, distributors and phase shifters may also be integrally formed, such that all that need be done after incorporation of the additional functional parts in these assemblies is to fit a cover as well.
Particularly if metalized plastic parts are used as the basis for the reflector, complete cable structures can also be integrated by suitable measures such as hot stamping, two-component injection molding methods, laser processing, etching methods or the like (“three-dimensional printed circuit board”).
Interfaces for holding components for attachment or mounting as well as interfaces for accessories, for example in the form of attachment flanges, heat flanges etc., can also be provided.